The proposed research will use videotaped records of spontaneous, rhythmic, stereotyped motility such as kicking and banging to examine the onset of bilateral limb coordination in 1-8 month old human infants. Bilateral coordination will be operationally defined as the presence of simultaneous or alternating movements of a bilateral limb pair (arm-arm or leg-leg). The proposed analysis should establish an earlier onset of bilateral coordination than is revealed by other voluntary but more complex and demanding weight-bearing movements such as walking and crawling which have similar temporal and kinematic properties. The proposed research will provide: 1) a description of the development of spontaneous bilateral limb coordination; 2) a sensitive, non-invasive (videotape) technique for measuring the development of bilateral coordination; 3) evidence concerning the maturation of the neural circuits producing bilateral coordination; 4) data concerning the development of bilateral symmetry/asymmetry; and 5) techniques and baseline data which should be useful for the early diagnosis of neuropathy. The results of the proposed research will be the first concerning the development of bilateral motor coordination which are based upon the spontaneous, rhythmic, stereotyped movements of human infants. The data should be of interest to pediatricians, neurologists, psychologists, and neuroembryologists interested in normal and abnormal human motor development.